I went with the BF Goodrich All-Terrain KO2.
http://www.tirerack.com/tires/tires....0KO2&tab=Sizes
They're a little pricey, but gives a good solid feel when I tow. I air them up to 65 PSI when towing. I usually run them just below 50 when unloaded. Having a 4wd truck, I wanted an AT tire.